Page-buffer and non-volatile semiconductor memory including page buffer

ABSTRACT

A non-volatile memory device includes a memory cell array which includes a plurality of non-volatile memory cells, a plurality of word lines, and a plurality of bit lines. The memory device further includes an internal data output line for outputting data read from the bit lines of the memory array, and a page buffer operatively connected between a bit line of the memory cell array and the internal data output line. The page buffer includes a sense node which is selectively connected to the bit line, a latch circuit having a latch node which is selectively connected to the sense node, a latch input path which sets a logic voltage of the latch node in the programming mode and the read mode, and a latch output path which is separate from the latch input path.

CROSS-REFERENCE TO RELATED APPLICATIONS

This is a Continuation application of application Ser. No. 12/752,213,filed Apr. 1, 2010, now U.S. Pat. No. 8,174,888, issued May 8, 2012,which is a Divisional application of application Ser. No. 12/035,028,filed Feb. 21, 2008, now U.S. Pat. No. 7,724,575, issued May 25, 2010,which is a Divisional application of application Ser. No. 11/228,189,filed Sep. 19, 2005, now U.S. Pat. No. 7,379,333 issued May 27, 2008,which is incorporated herein by reference in its entirety.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention generally relates to semiconductor memory devices,and more particularly, the present invention relates to page buffercircuits and other circuits utilized in non-volatile semiconductormemory devices.

2. Description of the Related Art

The demand for electrically programmable and electrically erasablenonvolatile memory devices has increased dramatically in recent years.Such devices are at least partially characterized by the ability tomaintain stored data even in the absence of supplied power. The use ofso-called flash memories has become especially popular, particularly,but not exclusively, in the context of portable devices such as digitalcameras, cell phones, personal data assistants (PDAs), and laptopcomputers. Flash memories, such as NAND-type flash memories, are capableof storing large amounts of data in a relatively small area.

As background discussion, the basic operating principles underlyingflash memory cells and flash memory devices are presented below.However, it should be clearly understood that the discussion thatfollows is merely exemplary and does not in any way limit and/or definethe scope of the present invention.

The operating principle of a flash memory cell will be described firstwith reference to FIGS. 1A through 1C. FIG. 1A illustrates a typicalconfiguration in which a flash memory cell transistor is connected toword and bit lines of a memory device, FIG. 1B shows the circuit symbolof a flash memory cell transistor, and FIG. 1C shows the thresholdvoltage characteristics of a flash memory cell transistor.

Referring collectively to FIGS. 1A through 1C, a flash memory celltransistor includes a source region 4 and a drain region 5 located atthe surface of a substrate 3. In this example, the substrate is P-type,and the source and drain regions 4 and 5 are N⁺-type. A gate structureis aligned over a channel region defined between the source and drainregions 4 and 5. The gate structure includes a floating gate 1 and acontrol gate 2. Although not shown, a tunneling dielectric layer isinterposed between the floating gate 1 and surface of the substratePsub, and another thin oxide layer (or control dielectric) is interposedbetween the floating gate 1 and the control gate 2. In the illustratedexample, the drain voltage Vd is supplied from a bit line BL, thecontrol gate voltage Vcg is supplied from a word line WL, and the sourcevoltage Vs is connected to a reference potential such as ground.

The threshold voltage of the flash memory cell transistor defines itsstored logic value. That is, when the flash memory cell transistor is inits initial state (also called an “erased” state), the threshold voltageVth is relatively low as shown in FIG. 1C. In this state, the celltransistor is designated to have a logic value “1”, which generallycorresponds to the ON state of a conventional transistor device. On theother hand, when the cell transistor is in its “programmed” state (PGM),the threshold voltage Vth is relatively high. This high threshold stateis designated to have a logic value “0”, which generally corresponds tothe OFF state of a conventional transistor device.

In order to change (program) the cell transistor from its initial stateto its programmed state, a process known as Fowler-Nordheim (FN)tunneling is utilized. Briefly, a relatively large positive potentialdifference is created between the control gate 2 and the substrate Psub,and excited electrons within the channel on the surface of the substratePsub are caused to be pushed through and trapped in the floating gate 1.These negatively charged electrons act as a barrier between the controlgate 2 and the channel on the substrate Psub, thus increasing thethreshold voltage of the cell transistor as represented in FIG. 1C. Thecell transistor can be brought back to its initial state by forming alarge negative potential difference between the control gate 2 and thesubstrate Psub, whereby resultant FN tunneling draws the trappedelectrons back across the thin oxide layer between the floating gate 1and substrate Psub, thus removing the electron barrier and decreasingthe threshold voltage Vth.

Turning now to FIG. 2, the ON and OFF threshold voltages Vth of thelarge numbers of flash cell transistors found in flash memory devicesgenerally exhibit bell curve distributions. For example, the thresholdvoltages Vth of the erased cell transistors (having logic value “1”) maybe distributed between −3v and −1v, whereas the threshold voltages Vthof the programmed cell transistors (having logic value “0”) may bedistributed between +1v and +3v.

Referring now to FIG. 3A, NAND flash memories are characterized byserially connected “strings” 6 of flash memory cell transistors, wheremultiple parallel strings 6 constitute a memory block 7 of the flashmemory. As shown, each string 6 is comprised of a plurality of flashmemory cell transistors connected in series along a bit line B/L in thememory block 7. Word lines W/L are connected to the control gates ofeach respective row of cell transistors in the memory block 7. Forexample, a flash memory device may contain 16 or 32 cell transistors ineach string 6, and 4224 strings (B/L0 . . . B/L4223) in each memoryblock 7.

At opposite ends of each string 6 are string select transistors havingcontrol gates which receive a string select signals SSL and a groundselect signal GSL. Generally, the select signals SSL and GSL areutilized in reading and programming of the cell transistors. Further, atthe end of each string is a common source line CSL which sets a sourceline voltage of the cell transistor strings 6 of each memory block 7.

The table of FIG. 3B generally shows the various voltage conditions ofthe signals illustrated in FIG. 3A for each of erase, program and readoperations. In this table, “Sel. W/L” denotes the selected word line forwhich the program or read operation is to be executed, and “Unsel. W/L”denotes the remaining word lines of the memory block. For the eraseoperation, “Sel. W/L denotes the word lines of the selected memory blockfor which the erase operation is to be executed, and “Unsel. W/L denotesthe word lines of the remaining memory blocks in the memory cell array.

A NAND flash programming operation will now be described with referenceto FIGS. 3B and 4. Here, string select signal SSL is set to VDD, groundselect signal GSL is set to 0v, the common source line CSL voltage isset to between VSS and VDD (e.g., 1.5v), and the bulk voltage is set to0v. Generally, programming occurs one word line at a time, andaccordingly, one word line is selected per memory block for eachprogramming operation. Here, the selected word line W/L receives aprogramming voltage Vpgm, while the remaining unselected word lines W/Lreceive a voltage Vpass, where Vpgm is greater than Vpass. Vpgm is of asufficiently high voltage (e.g., 18v) that FN tunneling results when thebit line B/L voltage of any cell transistor of the selected word line is0v. In other words, when the bit line B/L voltage of any cell transistorof the selected word line is 0v, the program voltage Vpgm creates avoltage difference (e.g., 18v) which is sufficient to initiate FNtunneling, thus placing the cell transistor in a programmed state. Onthe other hand, when the bit line B/L voltage of any cell transistor isVDD, FN tunneling is inhibited as a result of insufficient voltagedifference (e.g., 10v). As such, the cell is said to be “programinhibited”. In the meantime, the pass voltage Vpass is sufficiently highto place the non-selected cell transistors in a conductive state, butnot so high as to cause FN tunneling.

Referring to FIGS. 3B and 5, a read operation will now be described. Inthis case, string select signal SSL is set to Vread, ground selectsignal GSL is set to Vread, the common source line CSL voltage is set to0v, and the bulk voltage is set to 0v. As with programming, the readoperation typically occurs one word line at a time, and accordingly, oneword line is selected per memory block for each read operation. Here,the selected word line W/L is set to 0v, while the remaining unselectedword lines W/L receive a read voltage Vread. In this example, Vread is4.5v, which exceeds the threshold voltage distributions of the “1” and“0” cell transistors. Therefore, the cell transistors coupled to thenon-selected word lines become conductive. On the other hand, the 0vvoltage applied to the selected word line falls between the thresholdvoltage distributions of the “1” and “0” cell transistors. As such, onlythe “1” cell transistors connected to the selected word line becomeconductive, whereas the remaining cell transistors of the selected wordline are nonconductive. The result is a voltage difference among the bitlines B/L of the memory block. In the example given in the table of FIG.3B, a bit line B/L voltage of about 1.2v is read as having a “0” statecell transistor at the selected word line, and a bit line voltage ofless than 0.8v is read as having a “1” state cell transistor at theselected word line.

Referring to FIGS. 3B and 6, an erase operation will now be described.In this case, the bit lines B/L, string select signal SSL, ground selectsignal GSL, common source line CSL, and the word lines of the unselectedmemory blocks are all set to a floating state. On the other hand, theselected word line voltage is set to 0v, and the bulk voltage is set toVerase (e.g., 19-21v). As such, a negative voltage difference is formedbetween the control gate and the bulk, resulting in FN tunneling acrossthe gate oxide between the floating gate and the substrate. As a result,the threshold voltage distribution is reduced from the programmed “0”state to the erased “1” state. Note that all the cell transistors of theselected memory block are in the erased “1” state after the eraseoperation.

As previously mentioned, reading and programming of the memory block areexecuted one word line at a time within the memory block. In someapplications, however, it is more accurate to say that these operationsare executed “page by page” within the memory block. This concept isgenerally illustrated in FIG. 7. In the illustrated example, the bitlines BL <k:0> are divided into even and odd bit lines BL_E <k:0> andBL_O <k:0>. The cell transistors of each word line constitute pages ofthe memory block, and in the example of FIG. 7, each word line isconnected to an odd page and an even page of the memory block. As willbe explained in more below, the page buffers PB <k:0> contained in apage buffer block are utilized to transmit read data from, and programdata to, the flash memory block. Generally, one page buffer PB isprovided for each pair of odd and even bit lines.

FIG. 8 is a block diagram illustrating core elements of one example of aNAND-type flash memory, in which a so-called “Y-gating” technique isutilized to access bit lines of the memory. As shown, a plurality ofpage buffer blocks PBB <31:0> are connected via bit lines BL <255:0> toa memory cell array MCARR. Each page buffer block PBB interfaces witheight bit lines BL. Although not shown in FIG. 8, each bit line BL isactually constituted by a pair of odd and even bit lines as discussedpreviously in connection with FIG. 7.

A plurality of page buffer decoders PBDE <31:0> are operatively coupledto the respective page buffer blocks PBB <31:0>, y address lines Ya<7:0>, y address lines Yb <31:0>, and a global data bus GDB. As will beexplained in more detail below, the y address lines Ya <7:0> arecommonly applied to all of the page buffer decoders PBDE <31:0>, whereasindividual ones of the y address lines Yb <31:0> are applied to therespective page buffer decoders PBDE <31:0>. In other words, page bufferdecoder PBDE0 receives y addresses Ya <7:0> and Yb0, page buffer decoderPBDE1 receives y addresses Ya <7:0> and Yb1, and so on. Internal datalines IDB <255:0> are coupled between the page buffer blocks PBB <31:0>and page buffer decoders PBDE <31:0>. In the example of FIG. 8, eightinternal data lines IDB are provided between each corresponding pair ofpage buffer block PBB and page buffer decoder PBDE.

Also applied to the page buffer blocks PBB <31:0> are data inputselection signals DI and nDI, and latch signals LCH <7:0>, the functionsof which are described below in connection with FIG. 9.

FIG. 9 is a schematic circuit diagram for explaining the page buffers PBand the page buffer decoders PBDE illustrated in FIG. 8. For convenienceof explanation, FIG. 9 illustrates the page buffers PB <7:0> in aside-by-side arrangement (i.e., juxtaposed in the word line direction).In reality, however, the page buffers are stacked one over the other(i.e., juxtaposed in the bit line direction).

The page buffer decoder PBDE0 of FIG. 9 includes a first transistorconnected between the global data bus GDB and a common internal dataline IDBC, and a plurality of second transistors connected between thecommon internal data line and respective internal lines IDB <7:0> of thepage buffers PB <7:0>. As shown, the gate of the first transistorreceives the y address signal Yb0, while the respective gates of thesecond transistors receive the y address signals Ya <7:0>. It shouldthus be apparent that the y address Yb <31:0> is used to selected anyone of the page buffer blocks PBB <31:0>, and the y address Ya <7:0> isused to select a bit line BL within the selected page buffer block PBB.

The page buffer PB0 includes a latch circuit having a latch node CMNLAand an inverted latch node CMNLAn. First and second transistors of thepage buffer PB0 are respectively controlled by the data input selectionsignals DI and nDI, and these transistors are connected between internaldata line IDB0 and the inverted latch node CMNLAn and latch node CMNLA,respectively. Another transistor is controlled by a page buffer selectsignal PBSLT, and is connected between the latch node CMNLA and a sensenode NSEN0. The sense node NSEN0, which is connected to a memory cellstring of the memory cell array, is selectively connected to voltage VDDby operation of another transistor which is controlled by a load controlsignal PLOAD. Finally, two more transistors are connected in seriesbetween the internal data line IDB and a reference voltage VSS. One ofthese two transistors is controlled by the voltage appearing on thesense node NSEN0, while the other is controlled by the latch signalLCH<0>.

Briefly, in a programming operation, the latch circuit of the pagebuffer PB0 stores a logic value as dictated by the data input selectionsignals DI and nDI and the voltage of the internal data line IDB, andthis logic value (i.e., the voltage appearing on latch node CMNLA) isthen transferred to the bit line of the memory cell string forprogramming. Likewise, in a reading operation, the sensed voltageappearing on the sense node NSEN0 is temporarily stored in the latchcircuit, and then transferred to the global data bus GDB via theinternal data line IDB. Note that the internal data line IDB functionsas a shared input and output line.

Conventional non-volatile memory devices described above suffer from anumber of drawbacks, particularly as the layout area of the variouscircuits is reduced as the memory devices become more integrated to meetdemands for higher memory capacities. Without intending to provide anexhaustive listing, some examples of these drawbacks are discussedbelow.

Parasitic capacitive coupling between internal data lines can result asillustrated in FIG. 10. As mentioned previously, and as shown in FIG.10, the page buffers <7:0> of each page buffer block PBB are juxtaposed(stacked) in the bit line direction, i.e., between the page bufferdecoder PBDE and the memory cell array MCARR. Also illustrated are anumber of transistors which are controlled by a sense node blockingsignal SOBLK so as to selectively couple the sense nodes SON <7:0> tothe bit lines BL <7:0>, respectively.

The internal data lines IDB of the respective page buffers PB all extendin parallel to each other within the page buffer block PBB. As thelayout area of the page buffers PB is reduced, the pitch P betweenadjacent internal data lines IDB becomes smaller, and accordingly,capacitive coupling increases between adjacent internal data lines IDB.The resultant coupling noise between adjacent internal data lines IDBcan cause signal distortion and data errors.

The large parasitic capacitance of the internal data lines IDB can alsocreate a charge sharing condition with the low capacitive latch node ofthe latch circuit of each page buffer PB. In some cases, this can resultin the data being flipped. Further, the heavy output load of theinternal data lines IDB makes it necessary to increase the output drivecapability of the page buffers, which can be problematic when space andpower resources are limited.

Also, referring again to FIG. 8, the bus region of the illustratedexample includes 40 y address lines. This relatively large number oflines must be attended by a large layout area for the bus region of thedevice, thus occupying scarce space resources.

SUMMARY OF THE INVENTION

According to an aspect of the present invention, a non-volatile memorydevice is provided which is operable in a programming mode and a readmode. The memory device includes a memory cell array which includes aplurality of non-volatile memory cells, a plurality of word lines, and aplurality of bit lines. The memory device further includes an internaldata output line for outputting data read from the bit lines of thememory array, and a page buffer operatively connected between a bit lineof the memory cell array and the internal data output line. The pagebuffer includes a sense node which is selectively connected to the bitline, a latch circuit having a latch node which is selectively connectedto the sense node, a latch input path which sets a logic voltage of thelatch node, and a latch output path which is separate from the latchinput path and which sets as logic voltage of the internal data outputline according to the logic voltage of the latch node.

According to another aspect of the present invention, a non-volatilememory device is provided which includes a memory cell array whichincludes a plurality of non-volatile memory cells, a page buffer whichincludes a latch circuit for temporarily storing data read from andprogrammed into the non-volatile memory cells of the memory cell array,an internal data output line which outputs data read from the memorycell array and temporarily stored in the page buffer, a latch input pathwhich is separate from the internal data output line and which sets thelatch circuit when data is to be programmed into the non-volatile memorycells of the memory cell array and when data is read from thenon-volatile memory cells of the memory cell array.

According to still another aspect of the present invention, anon-volatile memory device is provided which includes a memory cellarray which includes a plurality of non-volatile memory cells, an inputdata bus which inputs data to be programmed into the non-volatile memorycells of the memory cell array, an output data bus which is separatefrom the input data bus and which outputs data read from thenon-volatile memory cells of the memory cell array, a latch circuit fortemporarily storing data read from and programmed into the non-volatilememory cells of the memory cell array, an internal data output lineconnected to the output data bus, a latch input path connected to theinput data bus which sets the latch circuit when data is to beprogrammed into the non-volatile memory cells of the memory cell array,and an output drive circuit which transfers read data temporarily storedin the latch circuit to the internal data output line.

According to yet another aspect of the present invention, a non-volatilememory device is provided which includes a memory cell array whichincludes a plurality of non-volatile memory cells, a plurality of wordlines, and a plurality of bit lines. The memory device further includesan internal data output line and a plurality of page buffers connectedto the memory cell array and the internal data output line. The pagebuffer are arranged one after the other to define a correspondingplurality of juxtaposed page buffer regions, where each of the pagebuffers includes a latch circuit which temporarily stores data read fromthe memory cell array, and an address gate connected between the latchcircuit and the internal data output line. The address gate isresponsive to an address signal to selectively output the data from thelatch circuit of each page buffer to the internal data output line.

According to another aspect of the present invention, a non-volatilememory device is provided which includes a memory cell array whichincludes a plurality of non-volatile memory cells, a plurality of wordlines, and a plurality of bit lines, where the plurality of bit linesextend lengthwise in a first direction. The memory device furtherincludes a shared internal data output line which outputs data read fromthe memory cell array, a plurality of internal data input lines, and aplurality of page buffers which are each operatively connected betweenthe memory cell array, the shared internal data output line, and theplurality of internal data input lines.

According to still another aspect of the present invention, anon-volatile memory device is provided which includes a memory cellarray which includes a plurality of non-volatile memory cells, and apage buffer which includes a local data input line and a latch circuit.The latch circuit is responsive to the local data input line totemporarily store data read from and programmed into the non-volatilememory cells of the memory cell array. The memory device furtherincludes a global data input line which supplies external input signals,where the external input signals include programming signals to programthe memory cell array and control signals to read the memory cell array,and a gate circuit which selectively outputs the external input signalsto the local data input line according to an address signal supplied tothe gate circuit.

According to yet another aspect of the present invention, a nonvolatilememory device is provided which includes a memory cell array whichincludes a plurality of non-volatile memory cells, a plurality of wordlines, and a plurality of bit lines. The memory device further includesan internal data output line which outputs data read from the memorycell array, a plurality of page buffers which are operatively connectedbetween the memory cell array and the internal data output line, and aplurality of address lines operatively connected to at least one gatecircuit of the plurality of page buffers.

According to another aspect of the present invention, a page buffer fora non-volatile memory device is provided. The page buffer includes alatch circuit including a latch node, an internal data input line whichcontrols a voltage of the latch node, an internal data output line whichis electrically isolated from the latch node, and an output drivecircuit which controls a voltage of the internal output data lineaccording to the voltage of the latch node.

According to still another aspect of the present invention, anonvolatile semiconductor memory device is provided which includes amemory cell array having a plurality of electrically programmable anderasable memory cells, a plurality of word lines, and a plurality of bitlines. The memory device further includes at least one page buffer blockincluding a plurality of page buffers and an internal data output line.The page buffers are respectively connected to the bit lines and each isenabled in response to at least one of a plurality of buffer selectionaddresses. The page buffers each store data corresponding to data on abit line thereof on a latch node thereof. The internal data output lineis shared between the plurality of page buffers and is driven by data ona latch node of an enabled page buffer. The internal data output line iselectrically isolated from latch nodes of the page buffers.

BRIEF DESCRIPTION OF THE DRAWINGS

The above and other aspects and features of the present invention willbecome readily apparent from the detailed description that follows, withreference to the accompanying drawings, in which:

FIGS. 1A through 1C are a schematic diagram of a flash memory cell, acircuit symbol of a flash memory cell, and a threshold voltagecharacteristic diagram of a flash memory cell, respectively;

FIG. 2 illustrates threshold voltage distributions of flash memorycells;

FIGS. 3A and 3B are a schematic diagram of NAND-flash memory cell block,and a table showing erase, program and read voltages of a NAND-flashmemory cell block, respectively;

FIG. 4 is a diagram for explaining the programming of the NAND-flashmemory cell block shown in FIG. 3A;

FIG. 5 is a diagram for explaining the reading of the NAND-flash memorycell block shown in FIG. 3A;

FIG. 6 is a diagram for explaining the erasing of the NAND-flash memorycell block shown in FIG. 3A.

FIG. 7 is a schematic diagram of a memory block and a page buffer block;

FIG. 8 is a schematic diagram of a conventional nonvolatile memorydevice;

FIG. 9 is a schematic diagram of a page buffer and a page buffer decodercontained in the nonvolatile memory device of FIG. 8;

FIG. 10 is diagram illustrating the layout of page buffers within thepage buffer block contained in the nonvolatile memory device of FIG. 8;

FIG. 11 is a block diagram of a nonvolatile semiconductor memory deviceaccording to an embodiment of the present invention;

FIG. 12 is a schematic diagram of an example of a memory array containedin the nonvolatile memory of FIG. 11;

FIG. 13 is a diagram of an example of a page buffer block contained inthe nonvolatile memory of FIG. 11;

FIG. 14 is a schematic diagram of an example of a page buffer containedin the page buffer block of FIG. 13;

FIG. 15 is a schematic diagram of an example of a page buffer decodercontained in the nonvolatile memory of FIG. 11;

FIGS. 16A and 16B are flow charts for describing a read mode of anonvolatile memory according to an embodiment of the present invention;

FIGS. 17 is a timing diagram for describing a read mode of a nonvolatilememory according to an embodiment of the present invention;

FIG. 18 is a flow chart for describing a programming mode of anonvolatile memory according to an embodiment of the present invention;

FIG. 19 is a timing diagram for describing a programming mode of anonvolatile memory according to an embodiment of the present invention;and

FIG. 20 is a timing diagram for describing erase mode of a nonvolatilememory according to an embodiment of the present invention

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

The present invention will now be described by way of preferred butnon-limiting embodiments.

FIG. 11 is a schematic block diagram of a nonvolatile semiconductormemory device according to an embodiment of the present invention.

Referring to FIG. 11, the nonvolatile semiconductor memory device ofthis example includes a memory cell array MCARR, page buffer blocksNWPBB<63:0>, first and second global input lines GDI and nGDI, a globaloutput line GDOUT, y address signal lines Yp<7:0>, Yq<7:0> and Yr<7:0>,read latch signal lines LCH<7:0>, and page buffer decoders NWDE<63:0>.

The memory cell array MCARR includes a matrix array of memory cells,word lines WL (not shown in FIG. 11) and bit lines BL<511:0>. In theexample of this embodiment, the memory cells are flash memory celltransistors.

Internal input lines IDI<63:0> and nIDI<63:0>, and internal output linesIDOUT<63:0>, are connected between the page buffer decoders NWDE<63:0>and corresponding page buffer blocks NWPBB<63:0>.

The first global input line GDI and the second global input line nGDItransmit input data of opposite logic states during predeterminedoperational intervals, such as a read mode, a program mode and an erasemode. As will be explained in more detail later, each of the page bufferdecoders NWDE<63:0> decodes the input data GDI and nGDI, together withthe y address data Yq<7:0> and Yr<7:0>, to output the data of theinternal input lines IDI<63:0> and nIDI<63:0>.

Also, each of the page buffer decoders NWDE<63:0> provides datacorresponding to the data on the internal output lines IDOUT<63:0> tothe global output line GDOUT.

The page buffer blocks NWPBB<63:0> are responsive to the latch signallines LCH<7:0> and the y address Yp<7:0>. As will be explained laterherein, the page buffer blocks NWPBB<63:0> function to temporarily storeand then transmit input data corresponding to data on the internal inputlines IDI<63:0> and nIDI<63:0> to the bit lines BL<511:0>, and totemporarily store and then transmit output data corresponding to data onbit lines BL<511:0> to the internal output lines IDOUT<63:0>.

FIG. 12 is a view of a portion of the memory cell array MCARR of FIG. 11according to the example of this embodiment. In particular, FIG. 12illustrates circuitry associated with the memory cell strings of thefirst bit line BL0 of FIG. 11. Bit lines BL<511:1> are similarlyconfigured.

As discussed above, the memory cell array MCARR generally includes amatrix array of memory cells MC, a plurality of word lines WL<n-1:0>,and a plurality of bit lines BL<511:0>. The memory cells MC of thenonvolatile semiconductor memory device of the embodiment are NAND-typeflash memory cells.

FIG. 12 illustrates the first and second strings STe0 and STo0 connectedto the even and odd bit lines BLe0 and BLo0 which make up the bit lineBL0 of FIG. 11. Each string STe0 and STo0 includes transistors atopposite ends of the memory cells MC which are connected to select linesSSL and GSL. As shown, the select lines SSL and GSL run parallel to theword lines WL<n-1:0>. Also, each string STe0 and STo0 terminates at acommon source line CSL.

The even and odd bit lines are connected to a bit line control blockBLCONBK. For ease of explanation and to simplify previously discussedFIG. 11, the bit line control block BLCONBK is described here as formingpart of the memory cell array MCARR. However, the bit line control blockBLCONBK may also be viewed as a circuit that is separate and distinctfrom the memory cell array MCARR.

In each of read, program and erase operational modes, the bit linecontrol block BLCONBK selects one of the even bit line BLe0 and the oddbit line BLo0 and connects the selected bit line to the bit line BL0.This operation is executed by the transistor 515 which is controlled bythe sense node blocking signal SOBLK, and by the transistors 513 and 514which are respectively controlled by the even bit line selection signalBLSLTe and the odd bit line selection signal BLSLTo.

In addition, the bit line control block BLCONBK functions to pre-chargeor condition the voltages of the even bit line BLe0 and the odd bit lineBLo0 in the read, program mode and erase operational modes. Transistors511 and 512 are provided for this purpose. That is, transistor 511 isresponsive to an even shielding signal SHLDe to selectively connect abit line power voltage BLPWR to the even bit line BLe0, and thetransistor 512 is responsive to an odd shielding signal SHLDo toselectively connect the bit line power voltage BLPWR to the odd bit lineBLo0.

FIG. 13 illustrates an example of the page buffer block NWPBB0illustrated in FIG. 11. The remaining page buffer blocks NWPBB<63:1>have similar configurations.

The page buffer block NWPBB0 of FIG. 13 includes a plurality of pagebuffers NWBUF<7:0>, an internal output line IDOUT0, a first internalinput line IDI0, and a second internal input line nIDI0. The pagebuffers NWBUF<7:0> store data that is transmitted to and received fromthe bit lines BL<7:0>, respectively.

The internal output line IDOUT0 is a common internal output line for thepage buffer block NWPBB0, and transmits output data corresponding to thedata stored in any one of the page buffers NWBUF<7:0>.

The first internal input line IDI0 and the second internal input linenIDI0 supply signals which control the storing of data in the pagebuffers NWBUF<7:0> based on input data.

In order to minimize the necessary layout area, the page buffersNWBUF<7:0> included in the page buffer block NWPBB0 are positioned in astacked structure, i.e., juxtaposed between the page buffer decoderNWDE0 and the memory cell array MCARR.

Each of the page buffers NWBUF<7:0> of the page buffer block NWPBB isconnected between the internal input lines IDI0 and nIDI0 and acorresponding one of bit lines BL<7:0>. Further, each is equipped with atransistor 870 a that is responsive to a bit line shutoff signal BLSHFto connect the corresponding bit line BL<7:0> to a respective sense nodeNSEN<7:0>.

Further, each of the page buffers NWBUF<7:0> receives a respective oneof y address signals Yp<7:0>. Contrary to the conventional memorydevice, in the example of this embodiment, these address signals Yp<7:0>are connected directly to the respective page buffers NWBUF<7:0> (alsosee FIG. 11). As will be explained later, this results in the dualadvantages of reducing the number of lines present in the bus region ofthe memory, and reducing the overall number of y address lines of thememory. Herein, the Yp<7:0> address signals are referred to as bufferselection address signals.

As shown in FIG. 13, the internal output line IDOUT0 preferably extendsin a direction in which the page buffers NWBUF<7:0> are stacked. Assuch, variations in transmission line distances from the respective pagebuffers NWBUF<7:0> to the internal output line IDOUT0 are minimized.This in turn increases signal uniformity when loading data from the pagebuffers NWBUF<7:0> to the internal output line IDOUT0, thus enhancingthe sensing margin of the non-volatile memory.

Further, in the example of the present embodiment, the internal outputline IDOUT0 is shared among the page buffers NWBUF<7:0>. One advantageresulting from this configuration is that the problems associated withparasitic coupling of the internal data lines IDB<7:0> of a conventionalmemory (see FIG. 10) can be avoided.

FIG. 14 illustrates an example of the page buffers NWBUF0 of FIG. 13.The remaining page buffers NWBUF<7:1> are similarly configured.

As shown in FIG. 14, the page buffer NWBUF0 includes the sensing nodeNSEN0, a latch unit 810, a latch transmission unit 820, a latch drivingunit 825, a sensing response unit 830, an output driving unit 840, abuffer selection unit 850, a sensing setting unit 860, a bit lineshutoff unit 870 and the internal output line IDOUT0. The sensing nodeNSEN0 receives data provided from the bit line BL0, and is connected tothe bit line BL0 through the bit line shutoff unit 870.

The bit line shutoff unit 870 controls the connection of the bit lineBL0 to the sensing node NSEN0 in response to a bit line shutoff signalBLSHF. Preferably, the bit line shutoff unit 870 is implemented using abit line shutoff transistor 870 a, which is a low voltage NMOStransistor gated in response to the bit line shutoff signal BLSHF.

The latch unit 810 includes a latch node NLAT which stores datacorresponding to data of the bit line BL0.

The latch driving unit 825 is enabled in response to the bufferselection address Yp0 to provide a predetermined latch driving voltage.In this example, the latch driving voltage is the ground voltage VSS,and is independent of the data on the first and second internal inputlines IDI0 and nIDI0 provided to the latch transmission unit 820. Thelatch driving unit 825 of this example includes a latch drivingtransistor 825 a, and preferably, the latch driving transistor 825 a isan NMOS transistor that is gated in response to the buffer selectionaddress Yp0 and has a source terminal connected to the ground voltageVSS.

The latch transmission unit 820 of this example includes first andsecond latch transmission transistors 820 a and 820 b. The first latchtransmission transistor 820 a provides the latch driving voltageprovided from the latch driving transistor 825 a to a node N810 a of thelatch unit 810 in response to the first internal input line IDI0.Preferably, the first latch transmission transistor 820 a is connectedto the latch driving transistor 825 a and is gated in response to thedata on the first internal input line IDI0. Therefore, if data of alogic “H” state is applied to the first internal input line IDI0 whenthe buffer selection address Yp0 is in a logic “H” state, the firstlatch transmission transistor 820 a provides the ground voltage VSS tothe node N810 a of the latch unit 810.

The second latch transmission transistor 820 b of this example providesthe latch driving voltage provided from the latch driving transistor 825a to the latch node NLAT of the latch unit 810 in response to the secondinternal input line nIDI0. Preferably, the second latch transmissiontransistor 820 b is connected in series with the latch drivingtransistor 825 a and is gated in response to the data on the secondinternal input line nIDI0. Therefore, if data of a logic “H” state isapplied to the second internal input line nIDI0 when the bufferselection address Yp0 is in a logic “H” state, the second latchtransmission transistor 820 b provides the ground voltage VSS to thelatch node NLAT of the latch unit 810.

That is, in the example of this embodiment, when the first latchtransmission transistor 820 a is turned ON, data of a logic “H” state isstored on the latch node NLAT. On the other hand, when the second latchtransmission transistor 820 b is turned ON, data of a logic “L” state isstored on the latch node NLAT.

In FIG. 14, RBIN1 and RBIN2 denote buffer input paths through which thelatch driving voltage is transmitted to the latch unit 810. That is, thetransmission path through the latch driving transistor 825 a and thefirst latch transmission transistor 820 a to the latch node NLAT isdesignated as the first buffer input path RBIN1, and the transmissionpath through the latch driving transistor 825 a and the second latchtransmission transistor 820 b to the latch node NLAT is designated asthe second buffer input path RBIN2.

The sensing response unit 830 of this example is driven by the sensingnode NSEN0 to selectively transmit a sensing response voltage to thelatch transmission unit 820, to thereby control the data stored at thelatch node NLAT. Preferably, the sensing response voltage is the groundvoltage VSS. The sensing response unit 830 includes, for example, asensing response transistor 830 a and an output sensing transistor 830b.

Preferably, the sensing response transistor 830 a is an NMOS transistorthat is gated in response to the data on the sensing node NSEN0. Theoutput sensing transistor 830 b is an NMOS transistor that is arrangedin series with the sensing response transistor 820 a and is providedwith a source terminal connected to the ground voltage VSS. When thesensing response transistor 830 a is turned on, the output sensingtransistor 830 b is responsive to a read latch signal LCH to provide thesensing response voltage to the latch unit 810 through the latchtransmission unit 820. Further, the latch node NLAT stores datacorresponding to the sensing node NSEN0 in response to the sensingresponse voltage.

The sensing setting unit 860 sets the sensing node NSEN0 at apredetermined setting voltage. In this example, the setting voltage is asupply voltage VDD, and the sensing setting unit 860 includes a sensingsetting transistor 860 a. The sensing setting transistor 860 a ispreferably a PMOS transistor that has a source terminal connected to thesupply voltage VDD (for example, 2.2V) and is gated in response to asensing setting signal /PLOAD.

The output driving unit 840 is enabled in response to the bufferselection address Yp0. When enabled, the output driving unit 840 drivesthe internal output line IDOUT0 to a predetermined drive voltage inresponse to the data stored on the latch node NLAT. As is apparent inFIG. 14, the internal output line IDOUT0 is separated from andelectrically isolated from the latch node NLAT and the buffer inputpaths RBIN1 and RBIN2.

The output driving unit 840 includes, for example, a first outputdriving transistor 840 a and a second output driving transistor 840 b.The first output driving transistor 840 a is gated by the data stored onthe latch node NLAT of the latch unit 810. In this example, the firstoutput driving transistor 840 a is turned on when the data stored on thelatch node NLAT of the latch unit 810 is logic “H”. The second outputdriving transistor 840 b is connected in series with the first outputdriving transistor 840 a. The second output driving transistor 840 b isgated in response to the buffer selection address Yp0 to drive theinternal output line IDOUT0 to the drive voltage. In the example, thedrive voltage is the ground voltage VSS which is connected to the sourceterminal of the first output driving transistor 840 a. Thus, accordingto this embodiment, when the data stored on the latch node NLAT is alogic “H” state, the internal output line IDOUT0 is driven to the groundvoltage VSS in response to a transition of the buffer selection addressYp0 to the logic “H” state.

The buffer selection unit 850 of this example controls the connection ofthe latch node NLAT with the sensing node NSEN0. In this example, thebuffer selection unit 850 includes a buffer selection transistor 850 a,which is an NMOS transistor gated in response to a buffer selectionsignal PBSLT. When the voltage level of the buffer selection signalPBSLT is changed to a logic “H” state, the data on the latch node NLATis transmitted to the sensing node NSEN0 through the buffer selectiontransistor 850 a, where it can then be transmitted to the bit line BL0.

FIG. 15 illustrates an example of the page buffer decoder NWDE0 shown inFIG. 11. The remaining page buffer decoders NWDE<63:1> may be similarlyconfigured.

The page buffer decoder NWDE0 has two primary functions. First, the pagebuffer decoder NWDE0 transmits output data corresponding to data on theinternal output line IDOUT0 to the global output line GDOUT. Second, thepage buffer decoder NWDE0 transmits data corresponding to input data onthe first global input line GDI and the second global input line nGDI tothe first internal input line IDI0 and the second internal input linenIDI0, respectively.

The page buffer decoder NWDE0 in the example of FIG. 15 includes firstto third decoder logic gates 1201, 1203 and 1205, an inverter 1206, anda decoder transistor 1207.

Herein, the y address signals Yq<7:0> are referred to as main selectionaddresses, and the y address signals Yr<7:0> are referred to assub-selection addresses (see FIG. 11).

The first decoder logic gate 1201 performs a logic operation on a mainselection address Yq0 and a sub-selection address Yr0, and outputs thelogic operation result as a block decoding signal/BLDEC. In thisexample, the first decoder logic gate 1201 is a NAND gate which executesNAND operation on the main selection address Yq0 and the sub-selectionaddress Yr0, and outputs the NAND operation results as the blockdecoding signal/BLDEC. In this case, when both the main selectionaddress Yq0 and the sub-selection address Yr0 are activated to a logic“H” state, the block decoding signal/BLDEC is activated to a logic “L”state.

The second decoder logic gate 1203 is enabled in response to the blockdecoding signal/BLDEC, and provides logic operation results to the firstinternal input line IDI0 in accordance with data on the first globalinput line GDI. In this example, the second decoder logic gate 1203 is aNOR gate which executes a NOR operation on the block decodingsignal/BLDEC and the first global input line GDI. In this case, thesecond decoder logic gate 1203 inverts the data on the first globalinput line GDI and provides the inverted result to the first internalinput line IDI0 when the block decoding signal/BLDEC is in a logic “L”state (i.e., when both the main selection address Yq0 and thesub-selection address Yr0 are in a logic “H” state).

The third decoder logic gate 1205 is enabled in response to the blockdecoding signal/BLDEC and provides logic operation results to the secondinternal input line nIDI0 in accordance with data on the second globalinput line nGDI. In this example, the third decoder logic gate 1205 is aNOR gate which executes a NOR operation on the block decodingsignal/BLDEC and the second global input line nGDI. In this case, thethird decoder logic gate 1205 inverts data on the second global inputline nGDI and provides the inverted data to the second internal inputline nIDI0 thereof when the block decoding signal/BLDEC is in a logic“L” state (i.e., when both the main selection address Yq0 and thesub-selection address Yr0 are in a logic “H” state).

The inverter 1206 inverts the block decoding signal/BLDEC to gate thedecoder transistor 1207. As such, in this example, the decodertransistor 1207 provides data on the internal output line IDOUT0 to theglobal output line GDOUT when the block decoding signal/BLDEC isactivated to a logic “L” state.

In the example of the present embodiment, the nonvolatile memoryincludes 64 page buffer decoders NWDE<63:0>. The page buffer decodersNWDE<63:0> are individually selected based on a combination of the mainselection addresses Yq<7:0> and sub-selection addresses Yr<7:0>. Themain selection addresses Yq<7:0> are used to select one of 8 groups(having 8 buffer decoders each) among the 64 page buffer decodersNWDE<63:0>, and the sub-selection addresses Yr<7:0> are used to selectany one of 8 page buffer decoders contained in the selected group. Also,as mentioned previously, the buffer selection addresses Yp<7:0> are usedto select individual ones of 8 page buffers associated with the selectedbuffer decoder.

As such, in the example of the present embodiment, the total number ofcolumn address bus lines is 24, which compares quite favorably to the 40column address lines of the conventional memory device illustrated inFIG. 8.

Also, as describe above, internal output line IDOUT0 is electricallyisolated from the latch node NLAT and the buffer input paths RBIN1 andRBIN2. Thus, distortion of data stored on the latch node NLAT of aselected page buffer (e.g., NWBUF0) can be minimized which mightotherwise result from data stored in other page buffers (e.g.,NWBUF<7:1>) and charged on the internal output line IDOUT0.

Examples of the read, program and erase operational modes of theabove-described embodiments will now be described. In each of theexplanations that follow, reference should also be made to previouslydiscussed FIGS. 11-15.

A read operational mode will be described first with reference to FIGS.16A and 16B.

FIG. 16A is a flowchart for describing a method of operating a pagebuffer NWBUF to output data stored in a selected memory cell MCsel (seeFIG. 12).

At step S910, the latch node NLAT is initialized to data of a logic “H”state (a “first logic state”) or a logic “L” state (a “second logicstate”). The initialization of the latch node NLAT may be performed byeither of the first internal input line IDI0 and the second internalinput line nIDI0.

In a normal read operational mode of the example of this embodiment, thelatch node NLAT is initialized to data of the second logic state. Forthe initialization of the latch node NLAT to the second logic state, thebuffer selection address Yp0 becomes a logic “H” pulse, and the secondinternal input line nIDI0 also becomes a logic “H” pulse. In this case,the first internal input line IDI0 maintains a logic “L” state. Then,the latch node NLAT is initialized to data of a logic “L” state, thatis, the second logic state.

On the other hand, in an erase verification read operational mode of theexample of this embodiment, the latch node NLAT is initialized to dataof the first logic state. For initialization of the latch node NLAT tothe first logic state, the buffer selection address Yp0 becomes a logic“H” pulse, and the first internal input line IDI0 also becomes a logic“H” pulse. In this case, the second internal input line nIDI0 maintainsa logic “L” state. Then, the latch node NLAT is initialized to data of alogic “H” state, that is, the first logic state.

At step S950, the data developed on the bit line BL0, which correspondsto the data stored in the selected memory cell MCsel, is stored on thelatch node NLAT.

FIG. 16B is a flowchart for describing the steps S951, S953 and S955which may be executed as the step S950 of FIG. 16A. In this example,execution of step S951 a is considered preferable, but may be omitted.

At step S951, the sensing node NSEN0 is adjusted to the supply voltageVDD, that is, the setting voltage, by the sensing setting transistor 860a of the sensing setting unit 860. The setting voltage controls thesensing response unit 830 (enabled in response to the read latch signalLCH) to provide the sensing response voltage to the latch transmissionunit 820. Further, the bit line shutoff signal BLSHF is changed to alogic “L” state.

In this example, Step S951 includes steps S951 a and S951 b. At stepS951 a, the voltage level of the sensing setting signal/PLOAD ismaintained at a first preliminary voltage VPRE1 for a predeterminedperiod of time, to prevent the undershooting of supply voltage VDD. Atstep S951 b, the sensing setting signal/PLOAD is changed to a logic “L”state.

At step S953, the sensing response unit 830 provides the sensingresponse voltage to the latch transmission unit 820 in response to thedata developed on the bit line BL0. In this example, Step S953 includessteps S953 a, S953 b and S953 c.

At step S953 a, the sensing setting signal/PLOAD becomes a logic “H”state. As such, the setting state of the sensing node NSEN0 is released,and the sensing node NSEN0 is changed to a floating state. Further, atstep S953 b, the bit line shutoff transistor 870 a is turned on, so thatthe floating sensing node NSEN0 is connected to the bit line BL0.Therefore, the sensing node NSEN0 receives the data developed on the bitline BL0.

Consequently, if the selected memory cell MCsel is an OFF cell, thevoltage level of the sensing node NSEN0 is maintained at about thesupply voltage VDD. On the other hand, if the selected memory cell MCselis an ON cell, the voltage level of the sensing node NSEN0 is maintainedat about the ground voltage VSS.

At step S953 c, the sensing response unit 830 selectively provides asensing response voltage according to the sensing node NSEN0 to thelatch transmission unit 820. That is, if the read latch signal LCH isgenerated as an “H” pulse when the selected memory cell MCsel is an OFFcell and the voltage level of the sensing node NSEN0 is maintained atabout the supply voltage VDD, the sensing response unit 830 provides thesensing response voltage (VSS in this example) to the latch transmissionunit 820. On the other hand, when the selected memory cell MCsel is anON cell and the voltage level of the sensing node NSEN0 is maintained atabout the ground voltage VSS, the sensing response voltage is notprovided to the latch transmission unit 820 even though the read latchsignal LCH is generated as an “H” pulse.

At step S955, the latch node NLAT is flipped in response to the sensingresponse voltage supplied to the latch transmission unit 820.

As discussed above in connection with step S910, in a normal readoperational mode, the latch node NLAT is initialized to data of thesecond logic state. In this case, at step S955, the first internal inputline IDI0 is in a logic “H” state and the second internal input linenIDI0 is in a logic “L” state. Therefore, when the selected memory cellMCsel is an OFF cell, that is, a programmed cell, the latch node NLAT isflipped from a logic “L” state (second logic state) to a logic “H” state(first logic state). However, when the selected memory cell MCsel is anON cell, that is, an erased cell, the latch node NLAT maintains thelogic “L” state (second logic state).

On the other hand, as also described above in connection with step S910,in the erase verification read operational mode, the latch node NLAT isinitialized to data of a first logic state. In this case, the firstinternal input line IDI0 is in a logic “L” state and the second internalinput line nIDI0 is in a logic “H” state at step S955. Therefore, if theselected memory cell MCsel is an OFF cell, that is, an unerased cell,the latch node NLAT is flipped from a logic “H” state (first logicstate) to a logic “L” state (second logic state). On the other hand, ifthe selected memory cell MCsel is an ON cell, that is, an erased cell,the latch node NLAT maintains the logic “H” state (first logic state).

Returning to FIG. 16A, at step S970, the output driving unit 840 iscontrolled by the data stored on the latch node NLAT. Therefore, theinternal output line IDOUT0 is selectively driven to a drive voltage,that is, the ground voltage VSS. That is, if the data stored on thelatch node NLAT is logic “H”, the internal output line IDOUT0 is drivento the ground voltage VSS in response to the buffer selection addressYp0. However, if the data stored on the latch node NLAT is logic “L”,the internal output line IDOUT0 maintains its initial logic state, whichis the supply voltage VDD, even when the buffer selection address Yp0changes to a logic “H” state.

An example of the normal read operation mode is described below ingreater detail with reference to the timing diagram of FIG. 17.

FIG. 17 is a normal read operational mode (read mode) timing diagramshowing various signal voltages and node voltages of the nonvolatilememory device illustrated in the examples of FIGS. 11 through 15. Again,reference should be made to these earlier figures in the explanationthat follows.

In the read mode, data written in a selected memory cell MCsel isfetched, and the fetched data is then output.

For purposes of explanation, the read mode illustrated in FIG. 17 isdivided into six intervals, namely, a bit line discharge and page bufferreset interval (hereinafter referred to as a “READ1 interval”), a bitline precharge interval (hereinafter referred to as a “READ2 interval”),a bit line develop interval (hereinafter referred to as a “READ3interval”), a sensing interval (hereinafter referred to as a “READ4interval”), a recovery interval (hereinafter referred to as a “READSinterval”), and a data fetch interval (hereinafter referred to as a“READ6 interval”).

Again, for purposes of explanation, the “READ1 interval” is divided intoa page buffer reset interval (hereinafter referred to as a “READ1 ainterval”) and a bit line discharge interval (hereinafter referred to asa “READ lb interval”). During the READ1 a interval, the latch node NLATof the page buffer is reset to a logic “L” state, that is, the groundvoltage VSS. Subsequently, during the READ1 b interval, the even bitline BLe0, the odd bit line BLo0 and the bit line BL0 are discharged tothe ground voltage VSS, that is, data of a logic “L” state.

Reset of the latch node NLAT during the READ1 a interval occurs asfollows. During the READ1 a interval, since the buffer selection addressYp0 is in a logic “H” state, the latch driving transistor 825 a isturned ON (tR1). Further, since both the main selection address Yq0 andthe sub-selection address Yr0 are logic “H”, the block decodingsignal/BLDEC is changed to a logic “L” state (tR2). In this case, thefirst global input line GDI is logic “H” and the second global inputline nGDI is logic “L”. Therefore, the first internal input line IDI0 islogic “L”, and the second internal input line nIDI0 is logic “H” (tR3).Therefore, the first latch transmission transistor 820 a is turned OFF,and the second latch transmission transistor 820 b is turned ON.Accordingly, the node N810 a of the latch unit 810 is changed to a logic“H” state, and the latch node NLAT is reset to a logic “L” state.

The discharge of the bit lines BLe0, BLo0 and the BL0 during the READ1 bwill now be described. For convenience, it is assumed here that theuppermost memory cell MCsel in the left memory cell string STe0 (FIG.12) is selected.

During the READ1 b interval, a read voltage VREAD (for example, 5V) isapplied to unselected word lines WL<n-2:0> and the ground voltage VSS isapplied to a selected word line WLn-1. Further, the read voltage VREADis applied to both the string selection line SSL and the groundselection line GSL, and the ground voltage VSS is applied to the commonsource line CSL.

Further, a bit line voltage line BLPWR maintains the ground voltage VSS,and the even shielding signal SHLDe, the odd shielding signal SHLDo, thevoltage levels of the even bit line selection signal BLSLTe and thesensing node blocking signal SOBLK are changed to the supply voltageVDD. Therefore, the bit lines BLe, BLe0 and BLo0 are discharged to theground voltage VSS, that is, data of a logic “L” state.

Next, during the READ2 interval, the even bit line BLe0 and the bit lineBL0 are precharged to a predetermined precharge voltage (for example,0.8V) to sense a data value in the selected memory cell MCsel.

Further, during the READ2 interval, a first voltage is applied to theselected word line WLn-1, and a second voltage is applied to theremaining unselected word lines WL<n-2:0>. In this example, the firstvoltage is the ground voltage VSS, and the second voltage is the readvoltage VREAD. Therefore, the ON/OFF state of the selected memory cellMCsel is controlled by the data stored therein. That is, if the datastored in the selected memory cell MCsel is logic “1”, the selectedmemory cell MCsel is in an ON state, while if the stored data is logic“0”, the selected memory cell MCsel is in an OFF state.

During the READ2 interval, the even shielding signal SHLDe is changed toa logic “L” state to turn off the NMOS transistor 511 for connecting theeven bit line BLe0 to the bit line voltage line BLPWR (tR4). Therefore,the discharge of the even bit line BLe0 and the bit line BL0 isreleased. At this time, the odd shielding signal SHLDo is maintained atthe supply voltage VDD, so that the NMOS transistor 512 maintains an ONstate. Therefore, the odd bit line BLo0 is maintained at the groundvoltage VSS, and functions as a shielding line between even bit linesBLe0.

Further, the voltage of the sensing setting signal/PLOAD is dropped fromthe supply voltage VDD to a first preliminary voltage VPRE1 for apredetermined period of time, and then drops to the ground voltage VSS(tR5). Therefore, the sensing setting transistor 860 a is turned on, sothat the sensing node NSEN0 is changed to the supply voltage VDD, whichis the setting voltage.

According to the example of this embodiment, the preliminary voltageVPRE1 of the sensing setting signal/PLOAD is about 1.0V, which isbetween the ground voltage VSS and the supply voltage VDD. The sensingsetting signal/PLOAD is maintained at the first preliminary voltageVPRE1 for the predetermined period of time so as to reduce power noiseresulting from undershooting.

In this case, the bit line shutoff signal BLSHF is changed to a secondpreliminary voltage VPRE2, which is between the supply voltage VDD andthe ground voltage VSS. As such, the sensing node NSEN0 and the bit lineBL0 become electrically connected to each other. As described above, thebit line shutoff signal BLSHF gates the bit line shutoff transistor 870a at the second preliminary voltage VPRE2, thus allowing the bit linesBL0 and BLe0 to be pre-charged to a given level due to current providedfrom the sensing setting transistor 860 a. Here, the given level islower than the second preliminary voltage VPRE2 by the threshold voltageof the bit line shutoff transistor 870 a.

In addition, the voltage levels of the even bit line selection signalBLSLTe and the sensing node blocking signal SOBLK are changed to theread voltage VREAD such that sufficient current flows through the bitline shutoff transistor 870 a.

Next, the READ3 interval is executed in which the bit line BL0 sensesdata stored in the selected memory cell MCsel and develops the data.

More precisely, during the READ3 interval, the bit line shutoff signalBLSHF is the ground voltage VSS to turn OFF the bit line shutofftransistor 870 a (tR6). As such, the bit line BL0 becomes electricallyisolated from the sensing node NSEN0, and the bit line BL0 proceeds todevelop the data.

If the selected memory cell MCsel is an ON cell, data on the bit lineBL0 is discharged to the common source line CSL. Therefore, the voltagelevel of the bit line BL0 approximates the ground voltage VSS. On theother hand, if the selected memory cell is an OFF cell, the voltagelevel of the bit line BL0 remains substantially unchanged (except forvariations resulting from leakage current).

The sensing setting transistor 860 a maintains an ON state for most ofthe READ3 interval, but is turned OFF (tR8) immediately before the endof the READ3 interval. The sensing node NSEN0 thus maintains the supplyvoltage VDD and becomes a floating state.

Next, the READ4 interval is executed in which the data developed on thebit line BL0, that is, data corresponding to the voltage level of thebit line, is stored on the latch node NLAT of the page buffer NWBUF0.

Here, the floating state of the sensing node NSEN0 generated during theREAD3 interval is initially maintained while the bit line shutoff signalBLSHF is changed to a third preliminary voltage VPRE3 to turn on the bitline shutoff transistor 870 a.

According to the example of this embodiment, the third preliminaryvoltage VPRE3 is between the ground voltage VSS and the supply voltageVDD, and is lower than the second preliminary voltage VPRE2 by apredetermined voltage difference which corresponds to a sensing margin.The voltage level of the sensing node NSEN0 is thus determined accordingto the voltage level developed on the bit line BL0.

In this case, the data value on the first internal input line IDI0changes to a logic “H” state (tR9), so that the first latch transmissiontransistor 820 a is turned ON.

In response to the read latch signal LCH, the latch node NLAT storesdata on the sensing node NSEN0 as determined by the voltage level of thebit line BL0, such data corresponding to the data stored in the selectedmemory cell MCsel.

That is, when the selected memory cell MCsel is an ON cell, the voltagelevel of the bit line BL0 and the sensing node NSEN0 is close to theground voltage VSS. Therefore, even though the read latch signal LCH isenabled to a logic “H” state, data on the latch node NLAT maintains alogic “L” state.

On the other hand, when the selected memory cell MCsel is an OFF cell,while the voltage level of the bit line BL0 and the sensing node NSEN0may slightly drop from the pre-charged voltage level due to theinfluence of leakage current, the voltage level is maintained at a logic“H” state since the bit line shutoff transistor 870 a cannot be turnedon due to the difference between the second and third preliminaryvoltages VPRE2 and VPRE3. Therefore, if the read latch signal LCH isenabled to a logic “H” state, the data on the latch node NLAT is flippedto a logic “H” state.

Next, the READ5 interval is executed in which the bit line BL0 and thesensing node NSEN0 are reset.

During the READ5 interval, the even shielding signal SHLDe is changed tothe supply voltage VDD, and both the even bit line selection signalBLSLTe and the sensing node blocking signal SOBLK are changed from theread voltage VREAD to the supply voltage VDD. Therefore, the bit lineBL0 and the sensing node NSEN0 are reset to the ground voltage VSS(tR11).

Further, the unselected word lines WL<n-2:0>, the string selection lineSSL and the ground selection line GSL are all changed from the readvoltage VREAD to the ground voltage VSS.

Next, the READ6 interval is executed in which data corresponding to thelatch node NLAT (stored during the READ4 interval) is output to theglobal output line GDOUT through the internal output line IDOUT0.

During the READ6 interval, the buffer selection address Yp0 and theblock decoding signal/BLDEC are activated in the form of respectivepulse signals. As a result, data corresponding to the latch node NLAT istransmitted to the global output line GDOUT through the internal outputline IDOUT0.

In the example of this embodiment, the global output line GDOUT ispre-charged to the supply voltage VDD by an output line pre-chargecircuit (not shown) before the block decoding signal/BLDEC is activated.

If the selected memory cell MCsel is an ON cell, data on the latch nodeNLAT is logic “L”, and accordingly, data transmitted on the globaloutput line GDOUT becomes a logic “H” state. On the other hand, if theselected memory cell MCsel is an OFF cell, data on the latch node NLATis a logic “H” state, and accordingly, data transmitted on the globaloutput line GDOUT is discharged to a logic “L” state.

A program operational mode (program mode) according to an embodiment ofthe present invention will now be described with reference to theflowchart of FIG. 18. The program mode is executed to load input data ina selected memory cell MCsel of the memory cell array.

At step S1110, the latch node NLAT is initialized. The latch node NLATis initialized to data of a first logic state (that is, a logic “H”state) or a second logic state (that is, a logic “L” state) by eitherthe first internal input line IDI0 or the second internal input linenIDI0. In the present example, the latch node NLAT is initialized to aprogram inhibited state, which is a first logic state (that is, logic“H” state), by the first internal input line IDI0.

At step S1130, the latch transmission unit 820 provides the latchdriving voltage, which is the ground voltage VSS provided from the latchdriving unit 825, to the latch unit 810 by either of the first andsecond internal input lines IDI0 and nIDI0. Further, the latch unit 810loads data of a first logic state (that is, logic “H” state) or a secondlogic state (that is, logic “L” state) on the latch node NLAT using thelatch driving voltage.

More specifically, if the input data is logic “H”, the buffer selectionaddress Yp0 becomes a logic “H” pulse, and the first internal input lineIDI0 also becomes a logic “H” pulse. In this case, the second internalinput line nIDI0 maintains a logic “L” state. Then, the latch node NLATmaintains the program inhibited state, which is a logic “H” state.

On the other hand, if the input data is logic “L”, the buffer selectionaddress Yp0 becomes a logic “H” pulse, and the second internal inputline nIDI0 also becomes a logic “H” pulse. In this case, the firstinternal input line IDI0 maintains a logic “L” state. The latch nodeNLAT is then changed from a logic “H” state to a logic “L” state.

Consequently, in the example of this embodiment, when data loading isperformed, the first internal input line IDI0 and the second internalinput line nIDI0 have opposite logic states. If data of a logic “H”state is transmitted to the first internal input line IDI0 when thebuffer selection address Yp0 is in a logic “H” state, the data of alogic “H” state is stored on the latch node NLAT of the latch unit 810.If instead data of a logic “H” state is transmitted to the secondinternal input line nIDI0, the data of a logic “L” state is stored onthe latch node NLAT of the latch unit 810.

At step S1150, data loaded on the latch node NLAT is transmitted to thebit line BL0. This process is explained in more detail below as stepsS1151 and S1153.

At step S1151, the buffer selection unit 850 is controlled to connectthe latch node NLAT to the sensing node NSEN0, and ultimately, to thebit line BL0. That is, the buffer selection signal PBSLT changes to alogic “H” level so as to turn ON the buffer selection transistor 850 a.The data on the latch node NLAT is then transmitted to the sensing nodeNSEN0.

At step S1153, the bit line shutoff unit 870 is controlled to connectthe sensing node NSEN0 with the bit line BL0. More specifically, in thisexample, the bit line shutoff signal BLSHF changes to a logic “H” levelso as to turn ON the bit line shutoff transistor 870 a. The data on thesensing node NSEN0 is then transmitted to the bit line BL0.

At step S1170, the selected memory cell MCsel is programmed tocorrespond to the data transmitted to the bit line BL0.

An example of the program mode is described below in greater detail withreference to the timing diagram of FIG. 19.

FIG. 19 is a program mode timing diagram showing various signal voltagesand node voltages of the nonvolatile memory device illustrated in theexamples of FIGS. 11 through 15. Again, reference should be made tothese earlier figures in the explanation that follows.

For purposes of explanation, the timing diagram of FIG. 19 is dividedinto eight intervals, namely, a page buffer setup interval (hereinafterreferred to as a “PROG1 interval”), a data loading interval (hereinafterreferred to as a “PROG2 interval”), a high voltage enabling interval(hereinafter referred to as a “PROG3 interval”), a bit line setupinterval (hereinafter referred to as a “PROG4 interval”), a programexecution interval (hereinafter referred to as a “PROG5 interval”), arecovery interval (hereinafter referred to as a “PROG6 interval”), averification read interval (hereinafter referred to as a “PROG7interval”), and a Y-scan interval (hereinafter referred to as a “PROG8interval”).

In the PROG1 interval, the latch node NLAT is adjusted to a programinhibited state before externally applied data is loaded. In thisembodiment, the program inhibited state represents a state in which theexecution of cell programming is not required with respect to externallyapplied specific data. In this example, when data of a logic “H” stateis externally applied, cell programming is not required.

In the present example, during the PROG1 interval, the buffer selectionaddress Yp0 is in a logic “H” state (tP1) so as to turn ON the latchdriving transistor 825 a. Further, since both the main selection addressYq0 and the sub-selection address Yr0 are in a logic “H” state, theblock decoding signal/BLDEC is activated to a logic “L” state. In thiscase, the first global input line GDI is an active pulse having a logic“L” state, and the second global input line nGDI is in a logic “H”state. Therefore, the first internal input line IDI0 is an active pulsehaving a logic “H” state (tP2), and the second internal input line nIDI0is in a logic “L” state. The first latch transmission transistor 820 ais therefore temporarily turned ON, and the second latch transmissiontransistor 820 b is in an OFF state. In this manner, the latch node NLATis set to the program inhibited state, i.e., a logic “H” state.

The PROG2 interval is executed next in which externally applied data isloaded on the latch node NLAT of the page buffer NWBUF0.

During the PROG2 interval, data corresponding to the externally inputdata is stored on the latch node NLAT in response to the first internalinput line IDI0 or the second internal input line nIDI0. Further, thedata stored on the latch node NLAT is provided through the buffer inputpaths RBIN1 and RBIN2. The logic state of the data stored on the latchnode NLAT in response to the first internal input line IDI0 is oppositeto the logic state of the data stored on the latch node NLAT in responseto the second internal input line nIDI0. That is, in this example, thedata stored on the latch node NLAT in response to the first internalinput line IDI0 is logic “H”, and the data stored on the latch node NLATin response to the second internal input line nIDI0 is logic “L”.

At time tP4 in the PROG2 interval, the buffer selection address Yp0 islogic “H”. Since both the main selection address Yq0 and thesub-selection address Yr0 are both logic “H”, the block decodingsignal/BLDEC is logic “L”. At this time, the first global input line GDIor the second global input line nGDI is changed to a logic “H” state.

That is, if the input data is logic “L”, the second global input linenGDI is changed to a logic “L” state. More precisely, the first internalinput line IDI0 is changed to a logic “L” state, and the second internalinput line nIDI0 is changed to a logic “H” state. Therefore, data of alogic “L” state is stored on the latch node NLAT.

On the other hand, if the input data is logic “H”, the first globalinput line GDI is changed to a logic “L” state. More precisely, thesecond internal input line nIDI0 is changed to a logic “L” state, andthe first internal input line IDI0 is changed to a logic “H” state.Therefore, data of a logic “H” state is stored on the latch node NLAT.

The PROG3 interval is executed next. Here, a group of high voltagepumping circuits (not shown) included in the nonvolatile semiconductormemory device is enabled. Generally, these circuits are for generating avoltage which is greater than the supply voltage VDD. In the example ofthis embodiment, the high voltage pumping circuit group includescircuits for generating a program voltage (VPGM, for example, 20V), apass voltage (VPASS, for example, 7 to 9V), a read voltage (VREAD, forexample, 5V), etc. Further, the high voltage pumping circuit group mayalso include a circuit for generating a boosting voltage VPP (not shown)which is utilized by a row decoder (not shown). For reference, thesupply voltage VDD in the example of the present embodiment is about 2.2V.

During the PROG4 interval, the even bit line BLe0 connected to theselected memory cell MCsel, that is, a selected bit line, is adjusted toa voltage level corresponding to data stored on the latch node NLAT.Further, the odd bit line BLo0 that is not connected to the selectedmemory cell MCsel, that is, an unselected bit line, is adjusted to aprogram inhibited state.

Also during the PROG4 interval, the voltage level of the bit linevoltage line BLPWR increases to the supply voltage VDD (tP5). Further,the voltage levels of the even shielding signal SHLDe and the oddshielding signal SHLDo increase to the read voltage VREAD (tP6).Therefore, without causing a voltage drop, the voltage levels of theeven bit line BLe0 and the odd bit line BLo0 are changed to the supplyvoltage VDD, which is the voltage of the bit line voltage line BLPWR.

Further, the voltage levels of the even bit line selection signal BLSLTeand the sensing node blocking signal SOBLK also increase to the readvoltage VREAD. The voltage level of the bit line shutoff signal BLSHFincreases to a voltage “VDD+Vt1”. In the present example, the voltage“Vt1” is a predetermined voltage of about 1.5 V.

Further, at the time tP7 of the PROG4 interval, after the lapse of apredetermined time period, the voltage level of the even shieldingsignal SHLDe decreases again to the ground voltage VSS. Further, afterthe buffer selection signal PBSLT is changed to a first referencevoltage VREF1 (tP8), it is changed again to a fifth voltage (tP9). Inthe example of this embodiment, the fifth voltage is equal to “VDD+Vt1”,and the first reference voltage VREF1 is about 1.3V, which is betweenthe ground voltage VSS and the fifth voltage.

The data stored on the latch node NLAT is transmitted to the even bitline BLe0 connected to the selected memory cell MCsel. That is, if thedata stored on the latch node NLAT is logic “L”, the voltage of the evenbit line BLe0 becomes “0V”. Further, if the data stored on the latchnode NLAT is logic “H”, the even bit line BLe0 maintains the supplyvoltage VDD.

The PROGS interval is executed next in which data transmitted to theeven bit line BLe0 is stored in the selected memory cell MCsel.

After a pass voltage VPASS is applied to a selected word line WLn-1 fora predetermined period of time, the program voltage VPGM, which is athird voltage, is applied to the selected word line (tP10). The programvoltage VPGM allows data corresponding to the voltage level of the evenbit line BLe0, that is, the bit line BL0, to be programmed in theselected memory cell MCsel. Further, the pass voltage VPASS is appliedto the unselected word lines WL<n-2:0> (tP11). Therefore, the unselectedmemory cells MC maintain their ON states without being programmed.

If data transmitted to the even bit line BLe0 is logic “H” during thePROG5 interval, the program inhibited state is maintained. On thecontrary, if the data transmitted to the even bit line BLe0 is logic“L”, the selected memory cell MCsel is programmed by F-N tunneling.Therefore, in this example, the memory cell MCsel in which data of alogic “L” state is stored can be designated as a “programmed cell”.

Also, during the PROG5 interval, the string selection line SSL ischanged to the supply voltage VDD, the ground selection line GSL is theground voltage VSS, and the common source line CSL has a voltage ofabout 1.5V.

The PROG6 interval is executed next in which word lines WL<n-1:0>, bitlines BL0, BLe0 and BLo0, and the sensing node NSEN0 are discharged tothe ground voltage VSS.

That is, during the PROG6 interval, the bit line voltage line BLPWRmaintains the ground voltage VSS. Also, the even shielding signal SHLDe,the odd shielding signal SHLDo, the even bit line selection signalBLSLTe, the sensing node blocking signal SOBLK, and the bit line shutoffsignal BLSHF are changed to the supply voltage VDD. Therefore, the wordlines WL<n-1:0>, the bit lines BL0, BLe0 and BLo0, and the sensing nodeNSEN0, are discharged to the ground voltage VSS.

Further, the buffer selection signal PBSLT is changed to the groundvoltage VSS to electrically isolate the bit line BL0 from the latch nodeNLAT.

The PROG7 interval is executed next to sense (verify) the dataprogrammed in the memory cell MCsel.

The operation performed during the PROG7 interval is almost identical tothat performed in the previously described read mode. However, the PROG7interval differs from the read mode in that a predetermined verificationread voltage is applied to the selected word line WLn-1 and theresetting of the page buffer NWBUF0 can be omitted. Since the remainingoperations performed during the PROG7 interval are similar to those ofthe read mode, a detailed description thereof is omitted here to avoidredundancy.

The PROG8 interval is executed next in which a determination is made asto whether the selected memory cell MCsel has been correctly programmedusing the data stored on the latch node NLAT during the PROG7 interval.

That is, during the PROG8 interval, if the data stored on the latch nodeNLAT is logic “H”, data of a logic “L” state is output to the globaloutput line GDOUT, so that a pass signal is generated. Further, if thedata on the latch node NLAT is logic “L”, data of a logic “H” state isoutput to the global output line GDOUT, so that a fail signal isgenerated.

When the fail signal is generated during the PROG8 interval, a programloop from the PROG4 interval to the PROG8 interval is repeated.Consequently, when the pass signal is generated, the program mode iscompleted.

An example of an erase operational mode (erase mode) is described belowwith reference to the timing diagram of FIG. 20.

FIG. 20 is an erase mode timing diagram showing various signal voltagesand node voltages of the nonvolatile memory device illustrated in theexamples of FIGS. 11 through 15. As before, reference should be made tothese earlier figures in the explanation that follows.

For purposes of explanation, the erase mode timing diagram of FIG. 20 isdivided into six intervals, namely, an erase execution interval(hereinafter referred to as an “ERS1 interval”), a first recoveryinterval (hereinafter referred to as an “ERS2 interval”), a secondrecovery interval (hereinafter referred to as an “ERS3 interval”), afirst verification read interval (hereinafter referred to as an “ERS4interval”), a second verification read interval (hereinafter referred toas an “ERS5 interval”), and a Y-scan interval (hereinafter referred toas an “ERS6 interval”).

In the ERS1 interval, an erase voltage VERS is applied to the bulk ofthe memory cells MC, and a sixth voltage is applied to selected wordlines to erase data from corresponding memory cells. In this example,the erase voltage VERS is about 20V, and the sixth voltage is about 0.3V(tE1). Further, unselected word lines are adjusted to a floating state.The voltage of these unselected word lines is close to the erase voltageVERS due to the coupling with the bulk (tE2). Therefore, an eraseoperation is not performed in the memory cells connected to theunselected word lines.

Also in the ERS1 interval, the even shielding signal SHLDe, the oddshielding signal SHLDo, the even bit line selection signal BLSLTe, andthe odd bit line selection signal BLSLTo, are changed to a voltage“VERS-Vt2” (tE3 to tE6), while the sensing node blocking signal SOBLKmaintains the supply voltage VDD (tE7). In this case, the voltage “Vt2”represents a threshold voltage of high voltage NMOS transistors. In thisexample, Vt2 is about 1.3V.

The ERS2 and ERS3 intervals are executed next in which the voltages ofthe bulk of the memory cells MC and the bit line BL0 are controlled tosense the data stored in the selected memory cell.

That is, during the ERS2 interval, the common source line CSL isdischarged. More precisely, the ERS2 interval is a period during whichthe bulk of the memory cell MC is floated and a voltage of “VERS-Vt”charged on the common source line CSL is discharged to the groundvoltage VSS.

Further, during the ERS3 interval, the bulk and the bit lines BL0, BLe0and BLo0 are discharged. That is, the bit line voltage line BLPWR ischanged to the ground voltage VSS (tE8), and the even shielding signalSHLDe, the odd shielding signal SHLDo, the even bit line selectionsignal BLSLTe and the odd bit line selection signal BLSLTo are changedto the supply voltage VDD (tE9 to tE12). Therefore, the bit lines BL0,BLe0 and BLo0 are discharged to the ground voltage VSS.

The ERS4 interval and the ERS5 interval are executed next in which thelatch node NLAT is set to sense any non-erased data of the memory cellMC. As such, the data in the memory cell MC is sensed and stored on thelatch node NLAT.

That is, during the ERS4 interval, the data of the memory cell MC thatis connected to the even bit line BLe0 and was not erased during theERS1 interval is sensed after the latch node NLAT is set to a logic “H”state. The operation performed during the ERS4 interval is similar tothat performed in the normal read mode. However, as described previouslyin connection with the read mode, the ERS4 interval and the normal readmode differ with respect to the value reset on the latch node NLAT. Thatis, in the normal read mode the latch node NLAT is reset to a logic “L”state, while the operation performed during the ERS4 interval resets thelatch node NLAT to a logic “H” state.

The operation performed during the ERS4 interval further differs fromthe normal read mode in that the sensing of the read data is performedby activation of the second internal input line nIDI0 during the ERS4interval. Remaining operations performed during the ERS4 interval areclosely similar to those performed in the read mode, and accordingly, adetailed description thereof is omitted here to avoid redundancy.

The ERS5 interval is a period during which the data in the memory cellMC connected to the odd bit line BLo0 was not been erased during theERS1 interval is sensed. The operation performed during the ERS5interval differs from that performed during the ERS4 interval in thatsetting of the latch node NLAT is not performed. Remaining operationsperformed during the ERS5 interval are closely similar to thoseperformed during the ERS4 interval, and accordingly, a detaileddescription thereof is omitted here to avoid redundancy.

The ERS6 interval is executed next in which a determination is made asto whether the erase operation for the memory cells MC has beencorrectly performed using the data sensed during the ERS4 and ERS5intervals.

If the latch node NLAT is logic “H” during the ERS6 interval, data of alogic “L” state is output to the global output line GDOUT, so that apass signal is generated. In contrast, if the latch node NLAT is logic“L”, data of a logic “H” state is output to the global output lineGDOUT, so that a fail signal is generated.

Therefore, when the pass signal is generated, the erase mode iscompleted.

During the ERS6 interval, the latch node NLAT maintains a logic “H”state when the memory cell is sensed as an ON cell with respect to boththe ERS4 and ERS5 intervals. If the even bit line BLe0 is connected toan OFF cell (non-erased), the latch node NLAT is discharged to theground voltage VSS during the ERS4 interval. Therefore, even if a memorycell MC connected to the odd bit line BLo0 is detected as an ON cellduring the ERS5 interval, data on the latch node NLAT is logic “L”.

Likewise, when the odd bit line BLo0 is connected to an OFF cell, thedata on the latch node NLAT becomes logic “L” during the ERS5 interval,even though the memory cell MC connected to the even bit line BLe0 is anON cell.

Therefore, the pass signal is generated only when both the even bit lineBLe0 and the odd bit line BLo0 are sensed as being connected to an ONcells.

Although the preferred embodiments of the present invention have beendisclosed for illustrative purposes, those skilled in the art willappreciate that various modifications, additions and substitutions arepossible, without departing from the scope and spirit of the invention.As one example only, although a NAND-type nonvolatile semiconductormemory device is shown and described in the present specification, itwill be apparent to those skilled in the art that the technical spiritof the present invention can also be applied to other types ofnonvolatile semiconductor memory devices, such as AND-type semiconductormemory devices. Therefore, the technical scope of protection of thepresent invention must be defined by the technical spirit of theaccompanying claims. In this regard, the phrase “connected to” andsimilar such phrases are not to be interpreted as requiring directconnection between elements.

1. A nonvolatile memory device comprising: a memory cell array whichincludes a plurality of non-volatile memory cells, a plurality of wordlines, and a plurality of bit lines; a data output line which outputsdata read from the memory cell array; a plurality of page buffers whichare operatively connected between the memory cell array and the dataoutput line; and a data input line connected to the page buffer, whereinthe data input line is electrically isolated from the data output line,wherein the page buffer comprises a latch circuit configured to storedata read from the memory cell array; a first transistor having a gateterminal connected to the latch circuit and a source terminal connectedto a ground voltage; and a second transistor having a gate terminalconnected to an address line, a source terminal electrically connectedto a drain terminal of the first transistor, and a drain terminalconnected to the data output line.
 2. The nonvolatile memory deviceaccording to claim 1, wherein the data output line is precharged at asupply voltage before output of the read data, the first transistor isgated by a logic voltage of the read data, and the second transistor isgated by a logic voltage of the address line; and the data output lineis discharged at the ground voltage.
 3. The nonvolatile memory deviceaccording to claim 1, wherein the data output line is precharged at asupply voltage before output of the read data, the first transistor isnot gated by a logic voltage of the read data, and the second transistoris gated by a logic voltage of the address line, and the data outputline maintains the supply voltage.
 4. The nonvolatile memory deviceaccording to claim 1, wherein the data output line is shared by aplurality of page buffers.
 5. The nonvolatile memory device according toclaim 1, wherein the latch circuit stores data to be programmed in thememory cell of the memory cell array, a first path through which thedata to be programmed is stored in the latch circuit is electricallyseparated from a second path through which the read data stored in thelatch circuit is output to the data output line.
 6. A nonvolatile memorydevice comprising: a memory cell array which includes a plurality ofnon-volatile memory cells, a plurality of word lines, and a plurality ofbit lines; a data output line which outputs data read from the memorycell array; a plurality of page buffers which are operatively connectedbetween the memory cell array and the data output line; and a data inputline connected to the page buffer, wherein the data input line iselectrically isolated from the data output line, wherein the page buffercomprises a latch circuit configured to store data read from the memorycell array; and an output driving unit gated by a logic voltage of anaddress line and configured to set a logic voltage of the data outputline, wherein, after the data output line is precharged at a supplyvoltage and the read data is stored in the latch circuit, the outputdriving unit is activated by the logic voltage of the address line todischarge the data output line at a ground voltage or to maintain thedata output line at the supply voltage.
 7. The nonvolatile memory deviceaccording to claim 6, wherein the output driving unit comprises: a firsttransistor having a gate terminal connected to the latch circuit and asource terminal connected to the ground voltage; and a second transistorhaving a gate terminal connected to the address line, a source terminalconnected to a drain terminal of the first transistor, and a drainterminal connected to the data output line.
 8. The nonvolatile memorydevice according to claim 6, wherein the data output line is dischargedto a source terminal of a first transistor through the first transistorand a second transistor.
 9. The nonvolatile memory device according toclaim 7, wherein the first transistor is gated by the logic voltage ofthe read data, and the second transistor is gated by the logic voltageof the address line, and the data output line is discharged at theground voltage.
 10. The nonvolatile memory device according to claim 7,wherein the first transistor is not gated by the logic voltage of theread data, and the second transistor is gated by the logic voltage ofthe address line, and the data output line maintains the supply voltage.11. A nonvolatile memory device comprising: a memory cell array whichincludes a plurality of non-volatile memory cells, a plurality of wordlines, and a plurality of bit lines; a data output line which outputsdata read from the memory cell array; a plurality of page buffers whichare operatively connected between the memory cell array and the dataoutput line; and a data input line connected to the page buffer, whereinthe data input line is electrically isolated from the data output line,wherein the page buffer comprises a latch circuit configured to storedata read from the memory cell array and store data to be programmed inthe memory cell array; an output driving unit including a firsttransistor gated by a logic voltage of a first address line, andconfigured to output a logic voltage according to the read data storedin the latch circuit to a data output line; and a latch driving unitincluding a second transistor gated by the logic voltage of a secondaddress line, and configured to drive the latch circuit.
 12. Thenonvolatile memory device according to claim 11, wherein the firsttransistor has one terminal connected to a third transistor, and theother terminal connected to the data output line, wherein a gateterminal of the third transistor is connected to the latch circuit, andthe second transistor has one terminal connected to a driving voltage,and the other terminal connected to the latch circuit.
 13. Thenonvolatile memory device according to claim 11, wherein the firstaddress line and the second address line are same line.